From time to time my GPS goes haywire and puts me 2,000 or 1,000 miles away. Since it's highly unlikely that I would be capable of traveling 2,000 miles in 5 minutes I suggest that the tracking (web side) ignores that GPS information when it is over supersonic speeds.

Sum between Current position & Last position = x feet traveled
1 Foot per Second = 0.681818181818182 Miles per Hour
So if they are traveling on a plane at 650MPH it would be around 57,240 feet a minute.

Anything over that should be ignored..Unless you have some users traveling above Mach 1 then you can make it an impossible number that humans can't travel at.